1. Field of the Invention
The present invention relates to a drawing processing apparatus capable of effectively extracting figure data serving as input data from image data in a CAD/CAM system and a geographic information management system.
2. Description of the Related Art
As a result of the growing popularity of CAD/CAM systems, there has recently been a great demand that figure information be able to be automatically read out from a drawing. One way of meeting this demand has been the development of various types of drawing input apparatuses which automatically extract piping network information as a numerical data from an arrangement plan, using a pattern recognition technique or to read various lines such as dimension lines in a mechanical drawing.
However, a number of drawings such as arrangement plans, include information which is superimposed on maps. In this case, to input drawing information (figure information) of the drawings to a CAD/CAM system and extract only desired information, map information and arrangement plan information have to be separated from each other. However, a drawing made up of a combination of map information and arrangement plan information usually includes various segments and thus tends to be very complicated. As a result, it is often very difficult for drawing input apparatuses to correctly extract the segments by pattern recognition, and to extract desired segment data as numerical data. In addition, there is the drawback that, in such circumstances, the processing speed and recognition performance of the drawing processing apparatus are greatly reduced.
As described above, the conventional drawing input apparatus has the drawbacks wherein the map information of the background of the drawing and the arrangement plan information written on the map are difficult to separate from each other and the performance of pattern recognition of the arrangement plan is therefore reduced in pattern recognition.
The above related art is reported in Dana H. Ballard and Christopher M. Brown, "COMPUTER VISION," Chapter 3, 3.2.3 Background Subtraction, 1982, pp. 72-73, and Azriel Rosenfeld, Avinash C. Kak, "DIGITAL PICTURE PROCESSING," Chapter 9, 9.2 REGISTRATION, 1982, pp. 23-31.